Inorg. Chem. 1984, 23, 4393-4394
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(Im-C) Ru should carry small oscillator strengths even in the reduced symmetry present in the complex. Second, the greater rI-r2separations calculated for Im-C (Table I) and expected for I m - C should cause this second C T absorption to be shifted toward higher energy (about 6000 cm-') relative to the corresponding LMCT of the Ru(1m-N) and Ru(1m-N) linkage isomers. Due to their expected weakness, they would probably be obscured by the tail of the intense ligand a a * absorption^.'^
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4393
Contribution from the Department of Chemistry, Berhampur University, Berhampur 760 007, Orissa, India
Acid Decomposition of Tris(dimethylglyoximato)nickelate(IV) in the Presence of Nucleophiles. Evidence for Substitution Inertness of the Nickel(1V) Complex S. Acharya, G. Neogi, and R. K. Panda*'
Received December 20, 1983
Concluding Remarks
First-order disappearance in the dissociation of metal chelates, independent of the concentration of added nucleophiles, is generally indicative of substitution lability of the chelate and a rate-determining dissociative reaction mechanism. In this paper we present evidence, based on the acid decomposition of potassium tris(dimethylglyoximato)nickelate(IV)l in the presence of various nucleophiles, (i) that the above mechanistic inference is not general for reactions of chelates of metals in higher oxidation states and (ii) that limiting first-order disappearance kinetics is consistent with a mechanism in which the substitution-inert Ni(1V) undergoes a rate-determining intramolecular ligand oxidation with a subsequent and rapid dissociation of the oxidized ligand. The products of acid decomposition of Ni(1V) were 3,4dimethylfurazan (3,4-dimethyl-1,2,5-oxadiazole)and [Ni(dmgH)2] at pH 24.5 and 3,4dimethylfurazan, Ni2+(aq),and dmgH2 at pH
